I have some weird behaviour from nvidia drivers so far. My systemparts that are involved:

nvidia GTX 560
Two Screens
Ubuntu 14.04, fresh update from 12.04,

When I execute sudo nvidia-settings and click on apply none of the adjustments are taking place. On closing nvidia-settings I get an error in the terminal:

(nvidia-settings:24231): GLib-CRITICAL **: Source ID 5984 was not found when attempting to remove it
The program 'nvidia-settings' received an X Window System error.
This probably reflects a bug in the program.
The error was 'BadValue (integer parameter out of range for operation)'.
(Details: serial 1154 error_code 2 request_code 157 minor_code 25)
(Note to programmers: normally, X errors are reported asynchronously;
that is, you will receive the error a while after causing it.
To debug your program, run it with the --sync command line
option to change this behavior. You can then get a meaningful
backtrace from your debugger if you break on the gdk_x_error() function.)